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[2].Skogvoll, et al. Dynamics and state transitions during resuscitation in OHCA.Resuscitation 2008;78:30–7.

http://dx.doi.org/10.1016/j.resuscitation.2012.08.172

Poster Presentations / Res

eferences

].Kerber RE, Becker LB, et al. Automatic external defibrillators for public accessdefibrillation: recommendations for specifying and reporting arrhythmia analy-sis algorithm performance, incorporating new waveforms, and enhancing safety.Circulation 1997;95:1677–82.

].Wik L, Kramer-Johansen J, et al. Quality of cardiopulmonary resuscitation duringout-of-hospital cardiac arrest. JAMA 2005;293:299–304.

].Aramendi E, Irusta U, et al. ECG spectral and morphological parameters reviewedand updated to detect adult and paediatric life-threatening arrhythmia. Physio-logical Measurement 2010;31:749–61.

].Neurauter A, Eftestøl T, et al. Improving countershock success prediction duringcardiopulmonary resuscitation using ventricular fibrillation features from higherECG frequency bands. Resuscitation 2008;79:453–9.

ttp://dx.doi.org/10.1016/j.resuscitation.2012.08.170

P112

simple shock advice algorithm for automated external defib-illators compliant with the American Heart Association’secommendations

nai Ayala ∗, Elisabete Aramendi, Erik Alonso, Unai Irusta, Dignaonzalez-Otero

University of the Basque Country UPV/EHU, Bilbao, Bizkaia, Spain

Purpose: Although many shock/no-shock discriminationarameters are public, shock advice algorithms (SAA) in commer-ial automated external defibrillators (AED) are proprietary. Themerican Heart Association (AHA) defined the accuracy require-ents and the composition of the rhythm databases to evaluateED SAA.1 The aim of this study is to describe a simple SAA basedn well-known discrimination parameters, fully compliant withhe AHA recommendations.

Materials: ECG records were gathered in-hospital and fromut-of-hospital cardiac arrest (OHCA) patients. All records werertefact-free, had a minimum duration of 3 s, contained a singlehythm type and within each rhythm type all patients were dif-erent. Three expert reviewers classified the records in the rhythmypes specified by the AHA statement. The database was split inwo, for algorithm development and testing. The test database con-ained: 200 ventricular fibrillation (VF), 99 ventricular tachycardiaVT), 256 asystole (AS), 145 normal sinus rhythm (NSR) and 159ther non-shockable rhythms (Others).

Methods: The algorithm processes the ECG in 3 s segments. First,t identifies asystole using a power-threshold on the filtered ECG2.5–30 Hz). Then, non-asystole segments are filtered (0.5–30 Hz)nd the shock/no-shock decision is given by a logistic regressionlassifier that combines three parameters: TCI,2 VFleak3 and Edgerequency (EF).4 A majority criterion was applied to classify theecords with several segments.

Results: The classifier, optimized using the developmentatabase, was: Y = 0.02·TCI + 14.12·VFleak + 0.50·EF-21.40Y < 0 shock, Y > 0 no-shock). For the test database sensitiv-ties/specificities and their one-sided lower 90% confidencentervals were: 99.0% (97.5%) for VF, 99.0% (96.5%) for VT, 100%99.2%) for AS, 99.3% (97.6%) for NSR and 95.6% (93.0%) for Others.

Conclusion: A simple SAA compliant with the AHA recommen-ations has been fully described. However, its performance shoulde tested for real OHCA episodes.

eferences

].Kerber RE, Becker LB, Bourland JD, et al. Automatic external defibrillators for public

access defibrillation: recommendations for specifying and reporting arrhythmiaanalysis algorithm performance, incorporating new waveforms, and enhancingsafety. Circulation 1997;95:1677–82.

].Thakor N, Zhu YS, Pan KY. Ventricular tachycardia and fibrillation detection by asequential hypothesis testing algorithm. IEEE Trans Biomed Eng 1990;37:837–43.

tion 83 (2012) e24–e123 e67

].Kuo S, Dillman R. Computer detection of ventricular fibrillation. In: Computers inCardiology. US: IEEE Computer Society Press; 1978. p. 347–349.

].Neurauter A, Eftestøl T, Kramer-Johansen J, et al. Improving countershock successprediction during cardiopulmonary resuscitation using ventricular fibrillationfeatures from higher ECG frequency bands. Resuscitation 2008;79:453–9.

http://dx.doi.org/10.1016/j.resuscitation.2012.08.171

AP113

Medical emergency responders integration and train-ing (MERIT) real-time ECG data in OHCA first responderresuscitation: Key messages

Gerard Bury ∗, Mairéad Egan, Mary Headon

University College Dublin, Dublin, Ireland

Introduction: The dynamics of resuscitation can be usefullyobserved by use of real-time ECG data; examples include recentinsights on ‘state transitions’ and the impact of adrenaline onPEA.1,2

This study uses real-time ECG data to explore cardiac arrestmanagement by GPs in a community setting.

Methods: Between 2006 and 2012, MERIT supported AEDs/ALStraining at 531 general practice sites in urban, rural and mixedareas. All Cardiac Arrests with Resuscitation Attempts (CARAs)involving these GPs are reported by quarterly survey; clinical andECG data are collated with a mean response rate of 89% (81–97%).This study reports on key findings from ECG data downloaded fromAEDs used in CARAs. In 123/286 CARAs (43%), a GP used a MERITAED; 87 (70.7%) ECG records were retrieved for analysis.

Results: Age, gender, location, witnessed arrest and outcomesare comparable with all CARAs. There were 14/87 (16.7%) sur-vivors, 1/41 (2.4%) in a non-shockable rhythm and 13/46 (28.3%)if shockable. 8/14 (57.1%) survivors received 1 shock, 3/14 (21.4%)2–4 shocks and 2/14 (14.3%) 5–15 shocks. Patients in a shockablerhythm increased from 43 (49.4%) initially to 47 (54%) with CPR.45/87 (51.7%) received ALS drugs but only 2/45 (4.4%) survived and12/14 survivors received no drugs. No survivors occurred after aresuscitation duration of 13 min. In 51/87 (58.6%) at least one statetransition occurred (median 2 overall).

Conclusions: These data confirm the impact of early CPR anddefibrillation and the poor outcomes of non-shockable rhythms.Drug therapy contributes in few cases and most survivors areresuscitated with small numbers of shocks and within 13 min.Community based survivors result principally from early CPR anddefibrillation.

References

].Nordseth T, et al. Dynamic effects of adrenaline in OHCA with initial PEA. Resus-citation 2012 [epub].